Microsoft security alert.

January 13, 2009

Advisory overview

Qualys Vulnerability R&D Lab has released new
vulnerability checks in the Qualys Cloud Platform to protect
organizations against
3 vulnerabilities
that were fixed in
1 bulletins
announced today by Microsoft. Customers can immediately audit
their networks for these and other new vulnerabilities by accessing
their Qualys subscription. Visit our blog to see how to prioritize remediation.

Microsoft SMB Remote Code Execution Vulnerability (MS09-001)

The Server Message Block (SMB) Protocol is a network file sharing protocol used to provide shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. It is a client-server implementation and consists of a set of data packets, each containing a request sent by the client or a response sent by the server.

The following remote code execution and denial of service vulnerabilities have been identified in Microsoft SMB protocol which occur when processing specially crafted SMB packets.

1) A vulnerability exists in the way SMB allocates space for a transaction structure and later tries to clear more memory than it should when a TRANS request is processed, allowing an attacker to take control of the system. (CVE-2008-4834)

2) A flaw exists in the way SMB allocates and clears a data structure relating to the OPEN2 command. SMB protocol software insufficiently validates the buffer size before writing to it, allowing attackers to take complete control of the system and allowing remote execution of code. (CVE-2008-4835)

3) A denial of service vulnerability exists due to the way "srv.sys" handles malformed SMB WRITE_ANDX packets sent to an interface that uses a Named Pipe as endpoint. This flaw allows remote attackers to send a specially-crafted network message to a computer running the Server service causing it to stop responding. (CVE-2008-4114)

Attempts to exploit any of the above listed vulnerabilities does not require authentication.

Microsoft has rated the issues as critical for Windows 2000, Windows XP, and Windows Server 2003, and moderate for Windows Vista, and Windows Server 2008.

An attacker who successfully exploits this vulnerability could install programs; view, change, or delete data; or create new accounts with full user rights. Successful exploitation also results in denial of service which causes the affected system to crash and stop responding.

Solution

Workaround:
TCP ports 139 and 445 should be blocked at the firewall to protect systems behind the firewall from attempts to exploit this vulnerability.
Impact of workaround: Blocking the ports can cause several windows services or applications using those ports to stop functioning.

Patch:
Following are links for downloading patches to fix the vulnerabilities:

These new vulnerability checks are included in Qualys
vulnerability signature
1.22.108-2.
Each Qualys account is automatically updated with the latest
vulnerability signatures as they become available. To view the
vulnerability signature version in your account, from the
Qualys Help menu, select the About tab.

Selective Scan Instructions Using Qualys

To perform a selective vulnerability scan, configure a scan profile to use the following options:

Ensure access to TCP ports 135 and 139 are available.

Enable Windows Authentication (specify Authentication Records).

Enable the following Qualys IDs:

90477

If you would like the scan to return the Windows Hostname, also include QID 82044 and ensure access to UDP port 137 is available.

If you would like to be notified if Qualys is unable to log on to a host (if Authentication fails), also include QID 105015.

In addition, prior to running a scan for these new vulnerabilities, you can estimate your exposure to these new threats by running the Risk Analysis Report, available from the Qualys Vulnerability Management Reports tab.